1. Field of the Invention
The present invention relates to a new gelatin coating composition and a hard gelatin capsule formed therefrom. More specifically, it relates to a gelatin coating composition composed of succinated gelatin (alone or in combination with unmodified gelatin) and polyethylene glycol, and a gelatin capsule made from the gelatin coating composition which easily disintegrates without becoming brittle.
2. Description of the Prior Art
Hard capsules are conventionally made from gelatin (unmodified gelatin) incorporated with a plasticizer such as glycerin and sorbitol. Such conventional hard capsules are referred to as ordinary gelatin capsules hereinafter.
Such ordinary gelatin capsules suffer from the disadvantage of having amino groups which readily react with drugs having aldehyde groups therein such as macrolide antibiotics. The reaction between the amino groups of the capsules and the aldehyde groups of the drugs gives rise to giant molecules, with the result that the capsules become insoluble to such an extent that they do not disintegrate within a certain period of time prescribed in the Pharmacopoeia of Japan. This problem is involved even in the long-term acceleration test at 40.degree. C. and 75% RH which should be attached to the application for the drug manufacturing license.
Under the situation, the present inventors had proposed a hard capsule made from succinated gelatin. See Japanese Patent Laid-open No. 186314/1986. This capsule, however, is inferior in mechanical strength to ordinary gelatin capsules and hence it is liable to break when it is filled with drug formulation or stored for a long time. Therefore, it has not yet been put to practical use.